Ron Fouchier has discussed his influenza H5N1 transmission experiments in ferrets at an ASM Biodefense Conference, clarifying several assumptions about the transmissibility of the virus in this animal model.
Two different influenza H5N1 strains were used for Fouchier’s experiments: a wild type virus, and a mutated virus (we’ll call it mutH5N1). He did not reveal the nature of the mutations in this virus but from previous reports they consist of changes introduced into the viral HA protein to allow binding to sialic acid receptors in the avian respiratory tract, and other changes selected during passage in ferrets.
Ferrets are housed in neighboring cages separated by steel grids to allow free air flow between cages. The cages are placed in a class 3 biosafety hood within a BSL3+ facility. A ferret in one cage is inoculated intranasally with virus, and then ferrets in neighboring cages are assayed for presence of virus in the respiratory tract. When ferrets are inoculated with wt H5N1 virus, viral replication ensues in the respiratory tract, but the virus is not transmitted to animals in neighboring cages. When ferrets are inoculated with mutH5N1, the virus is transmitted to 3/4 ferrets in neighboring cages. If the mutH5N1 virus is recovered from these animals and used to infect new ferrets, it is then transmitted to 2/2 ferrets in neighboring cages. The results are summarized in the following figure:
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2 comments:
In previous accounts we heard the virus was 75% lethal, then we heard that all the ferrets died. As alarming as it was, I didn't see anybody running around in the streets screaming or anything. Heck, the staff of nuclear power plants haven't even dusted off their pandemic preparedness plans. I know because I asked. I suppose the rain barrels I've installed at my home and the solar panels that are to follow constitute what the CDC would deem as "unnecessary full-blown panic."
We've got government agencies who are held liable for not swaggering their butts around in the name of stopping terrorists, but a naturally emerging pandemic is "nobody's fault." So what a surprise, we've got the government insisting that everyone act as if terrorism is the greatest risk from H5N1. No matter how many poultry deaths and human clusters crop up for months across the globe, the government's plan is to slap their forehead and say "Wow, who would have thought?"
I seems to me that somebody has deemed the results of the Fouchier experiment as inconvenient and what we're hearing is reflective of this. We have an American public that by and large are not only not preparing for a pandemic, they're not even taking the most basic measures to ease the sheer desperation if trade and travel are interfered with. Everyone's aware of the danger of tsunamis hitting our nuke plants because we've had that shot across the bow already. But not the possibility that pandemic understaffing will force shutdowns and nobody will be able to heat their chicken soup.
This is the latest example of a pattern on the part of the US government. When they're not making decisions as if there's no tomorrow, they're making decisions to make sure there isn't.
"Seems to me...
you don't wanna talk about it..
Seems to me...
You just turn your pretty head and walk away"...
"Walk Away" James Gang
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